Aromatics alkylation

ABSTRACT

The present invention provides a process for producing an alkylaromatic compound comprising the step of contacting an alkylatable aromatic compound with an alkylating agent under alkylation conditions in the presence of a alkylation catalyst comprising phosphorus and a porous crystalline inorganic oxide material having an X-ray diffraction pattern including the d-spacing maxima at 12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstrom.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to aromatics alkylation, and inparticular to the alkylation of benzene with ethylene and propylene toproduce ethylbenzene and cumene, respectively. In addition, theinvention is concerned with the alkylation of aromatics with long chain(C₆+) alkylating agents to produce long chain alkylbenzenes.

[0002] Ethylbenzene and cumene are valuable commodity chemicals whichare used industrially for the production of styrene monomer and phenol,respectively. In addition, long chain alkylbenzenes are useful aslubricant base stocks and as intermediates in the production ofdetergents.

[0003] Alkylation is one of the most important and useful reactions ofhydrocarbons. Lewis and Bronsted acids, including a variety of naturaland synthetic zeolites, have been used as alkylation catalysts.Alkylation of aromatic hydrocarbon compounds employing certaincrystalline zeolite catalysts is known in the art. In particular,alkylation of benzene with ethylene and propylene in the presence ofzeolite catalysts represents the preferred commercial techniques for theproduction of ethylbenzene and cumene.

[0004] For example, U.S. Pat. No. 4,992,606 describes the use of MCM-22in the alkylation of aromatic compounds, such as benzene, withalkylating agents having aliphatic groups with 1 to 5 carbon atoms, suchas ethylene and propylene. Similarly, U.S. Pat. No. 4,962,256 describesthe use of MCM-22 in the alkylation of aromatic compounds withalkylating agents having aliphatic groups with at least 6 carbon atoms.

[0005] The use of MCM-49 in the alkylation of aromatic compounds withshort chain alkylating agents is described in U.S. Pat. No. 5,371,310and in alkylation of aromatic compounds with long chain alkylatingagents is described in U.S. Pat. No. 5,401,896.

[0006] The use of MCM-56 in the alkylation of aromatic compounds withshort chain alkylating agents is described in U.S. Pat. Nos. 5,453,554and 5,557,024.

[0007] It is also known from U.S. Pat. No. 5,470,810 that the additionof phosphorus to MCM-22 improves the hydrothermal stability of theresulting catalyst for use in catalytic cracking.

[0008] U.S. Pat. No. 3,962,364 discloses that the addition of at least0.5 wt % phosphorus to a zeolite having a constraint index of 1-12, inparticular ZSM-5, increases the selectivity of the zeolite in the vaporphase alkylation of aromatic hydrocarbons with olefins.

[0009] According to the invention, it has now been found thatmodification of MCM-22 and certain related molecular sieve catalysts,such as MCM-49 and MCM-56, with phosphorus increases the activity of thecatalyst for the alkylation of aromatic compounds. In addition, thephosphorus modification increases the selectivity of the catalysttowards the monoalkylated product and enhances its stability against thehydrothermal deactivation which can occur during regeneration.

SUMMARY OF THE INVENTION

[0010] According to the invention, there is provided a process forproducing an alkylaromatic compound comprising the step of contacting analkylatable aromatic compound with an alkylating agent under alkylationconditions in the presence of an alkylation catalyst comprisingphosphorus and a porous crystalline inorganic oxide material having anX-ray diffraction pattern including the d-spacing maxima at 12.4±0.25,6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstrom.

[0011] Preferably, the porous crystalline inorganic oxide material isselected from the group consisting of MCM-22, PSH-3, SSZ-25, MCM-36,MCM-49 and MCM-56.

[0012] Preferably, the alkylating agent has an aliphatic group having 1to 5 carbon atoms.

[0013] Preferably, the aromatic hydrocarbon is benzene and thealkylating agent is selected from ethylene and propylene.

[0014] Preferably, said alkylation conditions are such as to maintainsaid alkylatable aromatic compound substantially in the liquid phase.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to a process for the production ofan alkylaromatic compound, particularly ethylbenzene or cumene, by thealkylation of an alkylatable aromatic compound, particularly benzene,with an alkylating agent, particularly ethylene or propylene, underalkylation conditions with a phosphorus-containing porous crystallineinorganic oxide material having an X-ray diffraction pattern includingthe d-spacing maxima at 12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07Angstrom.

[0016] The term “aromatic” in reference to the alkylatable compoundswhich are useful herein is to be understood in accordance with itsart-recognized scope which includes alkyl substituted and unsubstitutedmono- and polynuclear compounds. Compounds of an aromatic characterwhich possess a hetero atom are also useful provided they do not act ascatalyst poisons under the reaction conditions selected.

[0017] Substituted aromatic compounds which can be alkylated herein mustpossess at least one hydrogen atom directly bonded to the aromaticnucleus. The aromatic rings can be substituted with one or more alkyl,aryl, alkaryl, alkoxy, aryloxy, cycloalkyl, halide, and/or other groupswhich do not interfere with the alkylation reaction.

[0018] Suitable aromatic hydrocarbons include benzene, naphthalene,anthracene, naphthacene, perylene, coronene, and phenanthrene, withbenzene being preferred.

[0019] Generally the alkyl groups which can be present as substituentson the aromatic compound contain from 1 to about 22 carbon atoms andusually from about 1 to 8 carbon atoms, and most usually from about 1 to4 carbon atoms.

[0020] Suitable alkyl substituted aromatic compounds include toluene,xylene, isopropylbenzene, normal propylbenzene, alpha-methyinaphthalene,ethylbenzene, cumene, mesitylene, durene, p-cymene, butylbenzene,pseudocumene, o-diethylbenzene, m-diethylbenzene, p-diethylbenzene,isoamylbenzene, isohexylbenzene, pentaethylbenzene, pentamethylbenzene;1,2,3,4-tetraethylbenzene; 1,2,3,5-tetramethylbenzene;1,2,4-triethylbenzene; 1,2,3-trimethylbenzene, m-butyltoluene;p-butyltoluene; 3,5-diethyltoluene; o-ethyltoluene; p-ethyltoluene;m-propyltoluene; 4-ethyl-m-xylene; dimethyinaphthalene;ethylnaphthalene; 2,3-dimethylanthracene; 9-ethylanthracene;2-methylanthracene; o-methylanthracene; 9,10-dimethylphenanthrene; and3-methyl-phenanthrene. Higher molecular weight alkylaromatichydrocarbons can also be used as starting materials and include aromatichydrocarbons such as are produced by the alkylation of aromatichydrocarbons with olefin oligomers. Such products are frequentlyreferred to in the art as alkylate and include hexylbenzene,nonylbenzene, dodecylbenzene, pentadecylbenzene, hexyltoluene,nonyltoluene, dodecyltoluene and pentadecyltoluene. Very often alkylateis obtained as a high boiling fraction in which the alkyl group attachedto the aromatic nucleus varies in size from about C₆ to about C₁₂. Whencumene or ethylbenzene is the desired product, the present processproduces acceptably little by-products such as xylenes. The xylenes makein such instances may be less than about 500 ppm.

[0021] Reformate containing substantial quantities of benzene, tolueneand/or xylene constitutes a particularly useful feed for the alkylationprocess of this invention.

[0022] The alkylating agents which are useful in the process of thisinvention generally include any aliphatic or aromatic organic compoundhaving one or more available alkylating aliphatic groups capable ofreaction with the alkylatable aromatic compound.

[0023] Preferably, the alkylating agent employed herein has at least onealkylating aliphatic group possessing from 1 to 5 carbon atoms. Examplesof such alkylating agents are olefins such as ethylene, propylene, thebutenes, and the pentenes; alcohols (inclusive of monoalcohols,dialcohols and trialcohols) such as methanol, ethanol, the propanols,the butanols, and the pentanols; aldehydes such as formaldehyde,acetaldehyde, propionaldehyde, butyraldehyde, and n-valeraldehyde; andalkyl halides such as methyl chloride, ethyl chloride, the propylchlorides, the butyl chlorides and the pentyl chlorides.

[0024] Mixtures of light olefins are especially useful as alkylatingagents in the alkylation process of this invention. Accordingly,mixtures of ethylene, propylene, butenes, and/or pentenes which aremajor constituents of a variety of refinery streams, e.g., fuel gas, gasplant off-gas containing ethylene, propylene, etc., naphtha crackeroff-gas containing light olefins and refinery FCC propane/propylenestreams, are useful alkylating agents herein. For example, a typical FCClight olefin stream possesses the following composition: Wt. % Mole %Ethane 3.3 5.1 Ethylene 0.7 1.2 Propane 4.5 15.3 Propylene 42.5 46.8Isobutane 12.9 10.3 n-Butane 3.3 2.6 Butenes 22.1 18.32 Pentanes 0.7 0.4

[0025] Reaction products which may be obtained from the process of theinvention using short chain (C₁-C₅) alkylating agents includeethylbenzene from the reaction of benzene with ethylene, cumene from thereaction of benzene with propylene, ethyltoluene from the reaction oftoluene with ethylene, cymenes from the reaction of toluene withpropylene, and sec-butylbenzene from the reaction of benzene andn-butenes.

[0026] Alternatively, the alkylating agent used in the process of theinvention has one or more alkylating aliphatic groups with at leastabout 6 carbon atoms, preferably at least about 8, and still morepreferably at least about 12 carbon atoms. Examples of suitable longchain alkylating agents are olefins such as hexenes, heptenes, octenes,nonenes, decenes, undecenes and dodecenes; alcohols (inclusive ofmonoalcohols, dialcohols, and trialcohols) such as hexanols, heptanols,octanols, nonanols, decanols, undecanols and dodecanols; and alkylhalides such as hexyl chlorides, octyl chlorides, dodecyl chlorides;and, higher homologs of the foregoing. Branched alkylating agents,especially oligomerized olefins such as the trimers, tetramers andpentamers, of light olefins, such as ethylene, propylene and butylenes,are also useful herein.

[0027] The alkylation catalyst used in the process of the inventioncomprises phosphorus and a porous crystalline inorganic oxide materialhaving an X-ray diffraction pattern including d-spacing maxima at12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstrom. The X-raydiffraction data used throughout this specification were obtained bystandard techniques using the K-alpha doublet of copper as the incidentradiation and a diffractometer equipped with a scintillation counter andassociated computer as the collection system.

[0028] Suitable porous crystalline inorganic oxide materials are MCM-22(described in U.S. Pat. No. 4,954,325), PSH-3 (described in U.S. Pat.No. 4,439,409), SSZ-25 (described in U.S. Pat. No. 4,826,667), MCM-36(described in U.S. Pat. No. 5,250,277), MCM-49 (described in U.S. Pat.No. 30 5,236,575) and MCM-56 (described in U.S. Pat. No. 5,362,697). Allthe above U.S. patents are incorporated herein by reference.

[0029] The alkylation catalyst used in the process of the invention alsocontains phosphorus. The amount of phosphorus, as measured on anelemental basis, may be between about 0.05 and about 10 wt. %,preferably between about 0.1 and about 2 wt. %, and most preferablybetween about 0.1 and about 0.5 wt. %, based on the weight of the finalcatalyst.

[0030] Incorporation of the phosphorus modifier into the catalyst of theinvention is conveniently achieved by the methods described in U.S. Pat.Nos. 4,356,338, 5,110,776 and 5,231,064, the entire disclosures of whichare incorporated herein by reference. Treatment withphosphorus-containing compounds can readily be accomplished bycontacting the porous crystalline material, either alone or incombination with a binder or matrix material, with a solution of anappropriate phosphorus compound, followed by drying and calcining toconvert the phosphorus to its oxide form. Contact with thephosphorus-containing compound is generally conducted at a temperatureof about 25° C. and about 125° C. for a time between about 15 minutesand about 20 hours. The concentration of the phosphorus in the contactmixture may be between about 0.01 and about 30 wt. %.

[0031] Representative phosphorus-containing compounds which may be usedinclude derivatives of groups represented by PX₃, RPX₂, R₂PX, R₃P, X₃PO,(XO)₃PO, (XO)₃P, R₃P═O, R₃P═S, RPO₂, RPS₂, RP(O)(OX)₂, RP(S)(SX)₂,R₂P(O)OX, R₂P(S)SX, RP(OX)₂, RP(SX)₂, ROP(OX)₂, RSP(SX)₂, (RS)₂PSP(SR)₂,and (RO)₂POP(OR)₂, where R is an alkyl or aryl, such as phenyl radical,and X is hydrogen, R, or halide. These compounds include primary, RPH₂,secondary, R₂PH, and tertiary, R₃P, phosphines such as butyl phosphine,the tertiary phosphine oxides, R₃PO, such as tributyl phosphine oxide,the tertiary phosphine sulfides, R₃PS, the primary, RP(O)(OX)₂, andsecondary, R₂P(O)OX, phosphonic acids such as benzene phosphonic acid,the corresponding sulfur derivatives such as RP(S)(SX)₂ and R₂P(S)SX,the esters of the phosphonic acids such as dialkyl phosphonate,(RO)₂P(O)H, dialkyl alkyl phosphonates, (RO)₂P(O)R, and alkyldialkylphosphinates, (RO)P(O)R₂; phosphinous acids, R₂POX, such asdiethylphosphinous acid, primary, (RO)P(OX)₂, secondary, (RO)₂POX, andtertiary, (RO)₃P, phosphites, and esters thereof such as the monopropylester, alkyl dialkylphosphinites, (RO)PR₂, and dialkyl alkyphosphinites,(RO)₂PR. Corresponding sulfur derivatives may also be employed including(RS)₂P(S)H, (RS)₂P(S)R, (RS)P(S)R₂, R₂PSX, (RS)P(SX)₂, (RS)₂PSX, (RS)₃P,(RS)PR₂, and (RS)₂PR. Examples of phosphite esters includetrimethylphosphite, triethylphosphite, diisopropylphosphite,butylphosphite, and pyrophosphites such as tetraethylpyrophosphite. Thealkyl groups in the mentioned compounds preferably contain one to fourcarbon atoms.

[0032] Other suitable phosphorus-containing compounds include ammoniumhydrogen phosphate, the phosphorus halides such as phosphorustrichloride, bromide, and iodide, alkyl phosphorodichloridites,(RO)PCl₂, dialkylphosphorochloridites, (RO)₂PCl,dialkylphosphinochloridites, R₂PCl, alkyl alkylphosphonochloridates,(RO)(R)P(O)Cl, dialkyl phosphinochloridates, R₂P(O)Cl, and RP(O)Cl₂.Applicable corresponding sulfur derivatives include (RS)PCl₂, (RS)₂PCl,(RS)(R)P(S)Cl, and R₂P(S)Cl.

[0033] Particular phosphorus-containing compounds include ammoniumphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate,diphenyl phosphine chloride, trimethylphosphite, phosphorus trichloride,phosphoric acid, phenyl phosphine oxychloride, trimethylphosphate,diphenyl phosphinous acid, diphenyl phosphinic acid,diethylchlorothiophosphate, methyl acid phosphate, and otheralcohol-P₂O₅ reaction products.

[0034] After contacting with the phosphorus-containing compound, thecatalyst may be dried and calcined to convert the phosphorus to an oxideform. Calcination can be carried out in an inert atmosphere or in thepresence of oxygen, for example, in air at a temperature of about 150 to750° C., preferably about 300 to 500° C., for at least 1 hour,preferably 3-5 hours.

[0035] The porous crystalline oxide material employed in the alkylationcatalyst of the invention may be combined with a variety of binder ormatrix materials resistant to the temperatures and other conditionsemployed in the process. Such materials include active and inactivematerials such as clays, silica and/or metal oxides such as alumina. Thelatter may be either naturally occurring or in the form of gelatinousprecipitates or gels including mixtures of silica and metal oxides. Useof a material which is active, tends to change the conversion and/orselectivity of the catalyst and hence is generally not preferred.Inactive materials suitably serve as diluents to control the amount ofconversion in a given process so that products can be obtained in aneconomical and orderly manner without employing other means forcontrolling the rate of reaction. These materials may be incorporatedinto naturally occurring clays, e.g., bentonite and kaolin, to improvethe crush strength of the catalyst under commercial operatingconditions. Said materials, i.e., clays, oxides, etc., function asbinders for the catalyst. It is desirable to provide a catalyst havinggood crush strength because in commercial use it is desirable to preventthe catalyst from breaking down into powder-like materials. These clayand/or oxide binders have been employed normally only for the purpose ofimproving the crush strength of the catalyst.

[0036] Naturally occurring clays which can be composited with the porouscrystalline material include the montmorillonite and kaolin family,which families include the subbentonites, and the kaolins commonly knownas Dixie, McNamee, Georgia and Florida clays or others in which the mainmineral constituent is halloysite, kaolinite, dickite, nacrite, oranauxite. Such clays can be used in the raw state as originally mined orinitially subjected to calcination, acid treatment or chemicalmodification.

[0037] In addition to the foregoing materials, the porous crystallinematerial can be composited with a porous matrix material such assilica-alumina, silica-magnesia, silica-zirconia, silica-thoria,silica-beryllia, silica-titania as well as ternary compositions such assilica-alumina-thoria, silica-alumina-zirconia silica-alumina-magnesiaand silica-magnesia-zirconia.

[0038] The relative proportions of zeolite and inorganic oxide matrixvary widely, with the content of the former ranging from about 1 toabout 90% by weight and more usually, particularly when the composite isprepared in the form of beads, in the range of about 2 to about 80 wt. %of the composite.

[0039] The alkylation process of this invention is conducted such thatthe organic reactants, i.e., the alkylatable aromatic compound and thealkylating agent, are brought into contact with an alkylation catalystin a suitable reaction zone such as, for example, in a flow reactorcontaining a fixed bed of the catalyst composition, under effectivealkylation conditions. Such conditions include a temperature of fromabout 0° C. to about 500° C., and preferably between about 50° C. andabout 250° C., a pressure of from about 0.2 to about 250 atmospheres,and preferably from about 5 to about 100 atmospheres, a molar ratio ofalkylatable aromatic compound to alkylating agent of from about 0.1:1 toabout 50:1, and preferably can be from about 0.5:1 to about 10:1, and afeed weight hourly space velocity (WHSV) of between about 0.1 and 500hr⁻¹, preferably between 0.5 and 100 hr⁻¹.

[0040] The reactants can be in either the vapor phase or the liquidphase and can be neat, i.e., free from intentional admixture or dilutionwith other material, or they can be brought into contact with thezeolite catalyst composition with the aid of carrier gases or diluentssuch as, for example, hydrogen or nitrogen. Preferably, the alkylationconditions are such as to maintain the alkylatable aromatic compoundsubstantially in the liquid phase. For example, the alkylation reactioncan be conducted by reactive distillation.

[0041] When benzene is alkylated with ethylene to produce ethylbenzene,the preferred catalyst is phosphorus-modified MCM-22 and alkylationreaction is preferably carried out in the liquid phase. Suitable liquidphase conditions include a temperature between 300° F. and 600° F.(about 150° C. and 316° C.), preferably between 400° F. and 500° F.(about 205° C. and 260° C.), a pressure up to about 3000 psig (20875kPa), preferably between 400 and 800 psig (2860 and 5600 kPa), a spacevelocity between about 0.1 and 20 WHSV, preferably between 1 and 6 WHSV,based on the ethylene feed, and a ratio of the benzene to the ethylenein the alkylation reactor from 1:1 to 30:1 molar, preferably from about1:1 to 10:1 molar.

[0042] When benzene is alkylated with propylene to produce cumene, thepreferred catalyst is phosphorus-modified MCM-49 or phosphorus-modifiedMCM-56. The alkylation reaction is also preferably conducted underliquid phase conditions including a temperature of up to about 250° C.,e.g., up to about 150° C., e.g., from about 10° C. to about 125° C.; apressure of about 250 atmospheres or less, e.g., from about 1 to about30 atmospheres; and an aromatic hydrocarbon weight hourly space velocity(WHSV) of from about 5 hr⁻¹ to about 250 hr⁻¹, preferably from 5 hr⁻¹ to50 hr⁻¹.

[0043] The use of the phosphorus modifier in the alkylation catalyst ofthe invention is found to enhance the alkylation activity of thecatalyst over a wide range of aromatic compound to alkylating agentmolar ratios, thereby allowing operation at higher space velocities andhence increasing production capacity. In addition, the presence of thephosphorus is found to increase the selectivity of the catalyst for theproduction of the desired monoalkylated product and decrease itsselectivity for the production of polyalkylated products. Further, thephosphorus modification may increase the hydrothermal stability of thecatalyst, thereby enhancing its regenerability.

[0044] The alkylation reactor effluent contains the excess aromaticfeed, monoalkylated product, polyalkylated products, and variousimpurities. The aromatic feed is recovered by distillation and recycledto the alkylation reactor. Usually a small bleed is taken from therecycle stream to eliminate unreactive impurities from the loop. Thebottoms from the aromatic distillation are further distilled to separatemonoalkylated product from polyalkylated products and other heavies.

[0045] Additional monoalkylated product may be produced bytransalkylation. The polyalkylated products may be recycled to thealkylation reactor to undergo transalkylation or they may be reactedwith additional aromatic feed in a separate reactor. It may be preferredto blend the bottoms from the distillation of monoalkylated product witha stoichiometric excess of the aromatic feed, and react the mixture in aseparate reactor over a suitable transalkylation catalyst. Thetransalkylation catalyst may be a catalyst comprising a zeolite such asMCM-36, MCM-49, MCM-56, MCM-22, PSH-3, SSZ-25, zeolite X, zeolite Y,zeolite beta, or mordenite. Such transalkylation reactions over zeolitebeta are disclosed in the aforementioned U.S. Pat. No. 4,891,458; andfurther such transalkylations using an acid dealuminized mordenite aredisclosed in U.S. Pat. No. 5,243,116. Another particular form ofmordenite, which may be used as a transalkylation catalyst, is TEAmordenite, i.e., synthetic mordenite prepared from a reaction mixturecomprising a tetraethylammonium directing agent. TEA mordenite isdisclosed in U.S. Pat. Nos. 3,766,093 and 3,894,104. The effluent fromthe transalkylation reactor is blended with alkylation reactor effluentand the combined stream distilled. A bleed may be taken from thepolyalkyated product stream to remove unreactive heavies from the loopor the polyalkyated product stream may be distilled to remove heaviesprior to transalkylation.

[0046] The invention will be described with reference to the followingExamples.

EXAMPLE 1 Ethylbenzene Synthesis from Benzene and Ethylene OverUnmodified MCM-22

[0047] An MCM-22 catalyst was prepared as a 65/35 extrudate with 65 wt.% MCM-22 crystal with 35 wt % alumina. One gram of the catalyst wascharged to an isothermal, well-mixed Parr autoclave reactor along with amixture comprising of benzene (195 g) and ethylene (20 g). The reactionwas carried out at 428° F. and 550 psig for 4 hours. A small sample ofthe product was withdrawn at regular intervals and analyzed by gaschromatography. The catalyst performance was assessed by a kineticactivity rate constant based on ethylene conversion and by theethylbenzene selectivity at 100% ethylene conversion. The results forthe kinetic activity rate constant are given in Table 1 and for theethylbenzene selectivity are given in Table 2.

EXAMPLE 2 Ethylbenzene Synthesis from Benzene and Ethylene Over MCM-22Modified with Phosphorous Impregnated Via Phosphoric Acid (H₃PO₄)Solution

[0048] 0.1-10 grams of H₃PO4 were dissolved in 50 grams of distilledwater to yield a solution of pH ranging from 3.1 to 6.9. The resultingsolution was used to impregnate fifty grams of a fresh sample of theMCM-22 catalyst used in Example 1 by an incipient wetness method. Theimpregnated catalyst was dried at 250° F. for 12 hours in air followedby calcination at a temperature between 400 and 1200° F. in flowing airfor 4 hours. The resulting phosphorus weight loading varied from 0.5% to5%. One gram of the final catalyst was evaluated for benzene alkylationwith ethylene according to the procedure described in Example 1.Catalyst performance is compared with that of the unmodified MCM-22 ofExample 1 in Tables 1 and 2.

EXAMPLE 3 Ethylbenzene Synthesis from Benzene and Ethylene Over MCM-22Modified with Phosphorous Impregnated Via Dibasic Ammonium Phosphate((NH₄)₂HPO₄) Solution.

[0049] 0.1-10 grams of (NH₄)₂HPO₄were dissolved in 50 grams of distilledwater to yield a solution of pH ranging from 4.9 to 7.1. The resultingsolution was used to impregnate fifty grams of a fresh sample of theMCM-22 catalyst used in Example 1 by an incipient wetness method. Theimpregnated catalyst was dried at 250° F. for 12 hours in air followedby calcination at a temperature between 400 and 1200° F. in flowing airfor 4 hours. The resulting phosphorus weight loading varied from 0.5% to5%. One gram of the final catalyst was evaluated for benzene alkylationwith ethylene according to the procedure described in Example 1.Catalyst performance is compared with that of the unmodified MCM-22 ofExample 1 in Tables 1 and 2.

EXAMPLE 4 Comparison of Catalyst Performance

[0050] The performance of MCM-22 modified with phosphorous impregnatedvia an anionic precursor such as phosphoric acid (H₃PO₄) or dibasicammonium phosphate ((NH₄)₂HPO₄) is compared with unmodified MCM-22 inTables 1 and 2 below. The data in Table 1 represent kinetic rateconstants evaluated based upon ethylene conversion in the autoclaveaccording to the procedure outlined in Example 1. It will be seen fromTable 1 that the modification of the MCM-22 with phosphorus increasedits activity for benzene alkylation with ethylene by 27% in Example 2and by 37% in Example 3. TABLE 1 Catalyst Example 1 Example 2 Example 3Kinetic Rate Constant 41 52 56

[0051] The data in Table 2 represent the ethylbenzene selectivity at100% ethylene conversion according to the procedure outlined inExample 1. It will be seen from Table 2 that the modification of theMCM-22 with phosphorus increased its selectivity for ethylbenzeneproduction by decreasing its selectivity to diethylbenzene (by 12% inExample 2 and by 18% in Example 3) and by decreasing its selectivity totriethylbenzene (by 14% in Example 2 and by 29% in Example 3). TABLE 2Ethylbenzene DiEB/EB TriEB/EB Reduction in Reduction in Catalyst (EB)wt. % wt. % wt. % DiEB, wt. % TriEB, wt. % Example 1 91.9 8.5 0.35Example 2 92.8 7.5 0.3 11.7 14.2 Example 3 93.3 7 0.25 17.6 28.5

EXAMPLE 5 Cumene Synthesis from Benzene and Propylene Over UnmodifiedMCM-56.

[0052] MCM-56 catalyst was prepared as a 65/35 extrudate with 65 wt %MCM-56 crystal with 35 wt % alumina. One gram of the catalyst wascharged to an isothermal well-mixed Parr autoclave reactor along with amixture comprising of benzene (156 g) and propylene (28 g). The reactionwas carried out at 266° F. and 300 psig for 4 hours. A small sample ofthe product was withdrawn at regular intervals and analyzed by gaschromatography. The catalyst performance was assessed by a kineticactivity rate constant based on propylene conversion and cumeneselectivity at 100% propylene conversion. The results are given inTables 3 and 4.

EXAMPLE 6 Cumene Synthesis from Benzene and Propylene Over MCM-56Modified with 0.1 wt. % Phosphorus Impregnated Via Phosphoric Acid(H₃PO₄) Solution

[0053] 0.2 grams of H₃PO₄ were dissolved in 50 grams of distilled water,and the resulting solution was used to impregnate fifty grams of a freshsample of the MCM-56 used in Example 5 by an incipient wetness method.The impregnated catalyst was dried at 250° F. for 12 hours in airfollowed by calcination at 400° F. in flowing air for 4 hours, resultingin 0.1 wt. % P-loading. One gram of the final catalyst was evaluated forbenzene alkylation with propylene according to the procedure describedin Example 5. Catalyst performance is compared with that of unmodifiedMCM-56 in Table 3.

EXAMPLE 7 Cumene Synthesis from Benzene and Propylene Over MCM-56Modified with 0.5 wt. % Phosphorus Impregnated Via Phosphoric Acid(H₃PO₄) Solution

[0054] 1.0 grams of H₃PO₄ were dissolved in 50 grams of distilled waterand the resulting solution was used to impregnate fifty grams of a freshsample of the MCM-56 used in Example 5 by an incipient wetness method.The impregnated catalyst was dried at 250° F. for 12 hours in airfollowed by calcination at 400° F. in flowing air for 4 hours, resultingin 0.5 wt. % P-loading. One gram of the final catalyst was evaluated forbenzene alkylation with propylene according to the procedure describedin Example 5. Catalyst performance is compared with that of unmodifiedMCM-56 in Table 3.

EXAMPLE 8 Cumene Synthesis from Benzene and Propylene Over MCM-56Modified with 1.0 wt. % Phosphorus Impregnated Via Phosphoric Acid(H₃PO₄) Solution

[0055] 2.0 grams of H₃PO₄ were dissolved in 50 grams of distilled water,and the resulting solution was used to impregnate fifty grams of a freshsample of MCM-56 used in Example 5 by an incipient wetness method. Theimpregnated catalyst was dried at 250° F. for 12 hours in air followedby calcination at 400° F. in flowing air for 4 hours, resulting in 1.0wt. % P-loading. One gram of the final catalyst was evaluated forbenzene alkylation with propylene according to the procedure describedin Example 5. Catalyst performance is compared with that of unmodifiedMCM-56 in Table 3.

EXAMPLE 9 Cumene Synthesis from Benzene and Propylene Over MCM-56Modified with 2.0 wt. % Phosphorus Impregnated Via Phosphoric Acid(H₃PO₄) Solution

[0056] 4.0 grams of H₃PO₄ were dissolved in 50 grams of distilled water,and the resulting solution was used to impregnate fifty grams of a freshsample of MCM-56 used in Example 5 by an incipient wetness method. Theimpregnated catalyst was dried at 250° F. for 12 hours in air followedby calcination at 400° F. in flowing air for 4 hours, resulting in 2.0wt. % P-loading. One gram of the final catalyst was evaluated forbenzene alkylation with propylene according to the procedure describedin Example 5. Catalyst performance is compared with that of unmodifiedMCM-56 in Table 3.

EXAMPLE 10 Comparison of Catalyst Performance

[0057] The performance of MCM-56 modified with phosphorus impregnatedvia an anionic precursor such as phosphoric acid (H₃PO₄) is comparedwith unmodified MCM-56 in Table 3 below. The data represent kinetic rateconstants evaluated based upon propylene conversion as well as cumeneselectivity measured as the amount of di-isopropylbenzene formed perunit amount of cumene produced according to the procedure outlined inExample 5. It will be seen from Table 3 that modification of MCM-56 withphosphorus (0.1-0.5 wt. %) increased its activity for the alkylation ofbenzene with propylene and that modification of MCM-56 with phosphorus(0.1-1 wt. %) increases its selectivity to cumene rather thandiisopropylbenzene (DIPB). TABLE 3 DiPB/Cumene Catalyst Kinetic RateConstant (wt. %) Example 5 128 16.0 Example 6 140 13.1 Example 7 15513.1 Example 8 120 14.9 Example 9  95 17.5

EXAMPLE 11 Cumene Synthesis from Benzene and Propylene Over MCM-56Pretreated Under Hydrothermal Conditions

[0058] 25 g of the MCM-56 catalyst used in Example 5 were exposed to a80/20 mixture of steam and air at a GHSV of 300 h⁻¹ for 24 hours at 1000° F. One gram of the final catalyst was evaluated for benzene alkylationwith propylene according to the procedure described in Example 5, andcatalyst performance is described in Table 4.

EXAMPLE 12 Cumene Synthesis from Benzene and Propylene OverPhosphorus-modified MCM-56 Pretreated Under Hydrothermal Conditions

[0059] 25 g of finished catalyst from Example 7 was exposed to a 80/20mixture of steam and air at a GHSV of 300 h⁻¹ for 24 hours at 1000° F.One gram of the final catalyst was evaluated for benzene alkylation withpropylene according to the procedure described in Example 5, andcatalyst performance is described in Table 4.

EXAMPLE 13 Comparison of Catalyst Performance

[0060] The performance of MCM-56 modified with phosphorous and steamedis compared with unmodified steamed MCM-56 in Table 4 below. The datarepresent kinetic rate constants evaluated based upon propyleneconversion as well as cumene selectivity measured as the amount ofdiisopropylbenzene (DIPB) formed per unit amount of cumene producedaccording to the procedure outlined in Example 5. It will be seen fromTable 4 that the phosphorus-modified catalyst of Example 7 exhibitedsignificantly higher stability against hydrothermal deactivation thanthe unmodified catalyst of Example 5. TABLE 4 DiPB/Cumene CatalystKinetic Rate Constant (wt. %) Example 5  128 16.0 Example 7  155 13.1Example 11  10 26.0 Example 12  75 18.5

1. A process for producing an alkylaromatic compound comprising the stepof contacting an alkylatable aromatic compound with an alkylating agentunder alkylation conditions in the presence of an alkylation catalystcomprising phosphorus and a porous crystalline inorganic oxide materialhaving an X-ray diffraction pattern including the d-spacing maxima at12.4±0.25, 6.9±0.15, 3.57±0.07 and 3.42±0.07 Angstrom.
 2. The process ofclaim 1, wherein the porous crystalline inorganic oxide material isselected from the group consisting of MCM-22, PSH-3, SSZ-25, MCM-36,MCM-49 and MCM-56.
 3. The process of claim 1, wherein the alkylationcatalyst contains between about 0.05 and about 10 wt. % phosphorus, asmeasured on an elemental basis, based on the weight of the finalcatalyst.
 4. The process of claim 1, wherein the alkylation catalystcontains between about 0.1 and about 2 wt. % phosphorus, as measured onan elemental basis, based on the weight of the final catalyst.
 5. Theprocess of claim 1, wherein the alkylation catalyst contains betweenabout 0.1 and about 0.5 wt % phosphorus, as measured on an elementalbasis, based on the weight of the final catalyst.
 6. The process ofclaim 1, wherein the alkylation conditions are such as to maintain thealkylatable aromatic compound substantially in the liquid phase.
 7. Theprocess of claim 1, wherein the alkylating agent includes an aliphaticgroup having 1 to 5 carbon atoms.
 8. The process of claim 1, wherein thearomatic hydrocarbon is benzene and the alkylating agent is selectedfrom ethylene and propylene.
 9. The process of claim 1, wherein thearomatic hydrocarbon is benzene, the alkylating agent is ethylene andthe alkylation catalyst includes phosphorus and MCM-22.
 10. The processof claim 1, wherein the aromatic hydrocarbon is benzene, the alkylatingagent is propylene and the alkylation catalyst includes phosphorus andMCM-49 or MCM-56.